The use of deflectors which are fixed to a windshield wiper has proved necessary in order to avoid disengagement of the wiper under the influence of the aerodynamic forces which are set up by the air flows impinging on the wiper blade, and on its connection with the wiper arm, when the vehicle is travelling at high speed. Such deflectors ought ideally to have a free edge as close as possible to the glass that is to be swept. This is in order to reduce the gap between the glass and the free edge of the deflector, since air tends to be funnelled at high speeds through this gap when the vehicle is travelling fast.
However, the possibility of obtaining such close proximity between the free edge of the deflector and the glass is limited in practice, firstly by the curvature of the windshield, and secondly by the risk that the free edge of the deflector can come into contact with the glass, with a consequent risk of abrasion of the glass. This would in due course be detrimental to good visibility by the driver.
In order to overcome this disadvantage, in the published patent application No. DE 3 637 348A of the Federal Republic of Germany, it has been proposed that the lower part of the deflector, that is to say the part closest to the glass, should be in a material that is generally softer than the remainder of the deflector. This arrangement does however make it necessary not only to manufacture the deflector in two parts, but also to introduce the resulting problem of ensuring that the joint between these two parts is not easily separated. Such an assembly is therefore costly, and the joint between the two parts can be detrimental both to the aesthetic appearance of the wiper and to the aerodynamic characteristics.
In published European patent application No. EP 0 210 420A, it is proposed to mould a deflector in synthetic material on to a windshield wiper arm. Such a deflector gives no protection to the wiper blade and to the interface of the latter with the remainder of the windshield wiper, due to the position of the deflector on the wiper arm. In addition, in such an arrangement the deflector cannot be very securely fixed on the arm, which has a transverse cross section that is very small by contrast with the overall cross section of the wiper itself.